Thirty years on from the Bhopal disaster, an international film opens on Friday dramatising the story of how an American pesticide factory in India accidentally released cyanide gas into the atmosphere, killing thousands of people and leaving many more sick or disabled.

New Delhi: Thirty years on from the Bhopal disaster, an international film opens on Friday dramatising the story of how an American pesticide factory in India accidentally released cyanide gas into the atmosphere, killing thousands of people and leaving many more sick or disabled.

The thriller "Bhopal: A Prayer for Rain", starring Hollywood actors Martin Sheen and Kal Penn, documents events leading up to the world`s worst industrial disaster and its devastating aftermath.

Indian director Ravi Kumar said he hoped the film would help to ensure another such tragedy never occurred again.

"The template for most man-made industrial disasters is familiar - cost-cutting, pressure to make more money, callous attitude of corporate bosses in an exotic location," Kumar told the Thomson Reuters Foundation.

"We can learn from our mistakes and make sure Bhopal doesn`t happen again."

In the early hours of Dec. 3, 1984, around 40 metric tonnes of toxic methyl isocyanate (MIC) gas from Union Carbide`s pesticide plant in Bhopal leaked into the atmosphere and was carried by the wind to the surrounding slums.

The Indian government says around 3,500 died as a result of the disaster. Activists using mortality rates for survivors issued by the Indian Council for Medical Research calculate that 25,000 people died both in the immediate aftermath and in the years that followed.

Activists say a further 100,000 people who were exposed to the gas continue to suffer today from sicknesses such as cancer, blindness, respiratory difficulties, immune and neurological disorders and female reproductive disorders. Children of affected women have been born with birth defects, they add.

The film, which also stars Bollywood actors Rajpal Yadav and Tannishtha Chatterjee, was released in the United States on Friday. It will be screened in Bhopal on Dec. 3, the disaster`s 30th anniversary, and officially released in India on Dec. 5.

COMPENSATION CLAIMS

Human rights groups hope the film`s release will boost a waning decades-long campaign to get adequate compensation for thousands of the affected slum dwellers who continue to live around the abandoned factory.

Environmentalists claim the site is still contaminated and "a disaster within a disaster" is occurring as it slowly poisons the drinking water of thousands of Indians.

U.S. company Dow Chemical, which now owns Union Carbide, has long denied liability, saying it bought the company a decade after Union Carbide had settled its liabilities to the Indian government in 1989 by paying $470 million.

The company adds that the contamination of the site is not the responsibility of Dow Chemical, but of Indian authorities who took control of the site in 1998.

American actor Martin Sheen - who plays the character of Union Carbide`s CEO Warren Anderson in the film - has joined Amnesty International`s campaign to hold to account those responsible for the disaster.

"Those who survived have faced long-term health problems, but receive little medical help. For 30 years the survivors of Bhopal have campaigned for justice, for fair compensation, health care and for Union Carbide, now owned by Dow Chemicals, to be held to account," said Martin Sheen in statement.

"This was not an unavoidable accident. There is evidence that the companies responsible for the factory site failed to take adequate precautions both before and after the leak."

Anderson, who left the country soon after the disaster, was sought by the Indian government which had called for his extradition from the United States. He died in September, aged 92.

Dow Chemical is facing a legal case in the Bhopal court on Nov. 12 over Union Carbide`s refusal to answer charges of culpable homicide.

Kal Penn, who plays the role of an Indian journalist trying to uncover the truth behind the disaster, said he hoped the film`s themes of corporate greed and human rights violations would create greater awareness.

"I hope that, as we have seen in early screenings, the film allows us to think respectfully about how we can right the wrongs of the past, and also prevent future atrocities from taking place," Penn told the Thomson Reuters Foundation.